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Introduction to Biophysics

Introduction to Biophysics. Chapter 1 What the Ancients Knew Energy, Information, Life. Heat. What is the interplay between heat and work? Living systems do not function a low temperature Heat is a form of energy Falling rock - E = mgz + ½ mv 2 Mechanical = potential + kinetic

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Introduction to Biophysics

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  1. Introduction to Biophysics Chapter 1 What the Ancients Knew Energy, Information, Life

  2. Heat • What is the interplay between heat and work? • Living systems do not function a low temperature • Heat is a form of energy • Falling rock - E = mgz + ½ mv2 • Mechanical = potential + kinetic • Friction converts mechanical energy into thermal form. Energy accounts balance (total energy = mechanical energy + heat)

  3. Energy Conversion • Friction is a process of energy conversion • Conversion of energy from the sun into useful work • Conversion can be two-way, some energy is lost as heat in the conversion (one-way conversion). • “Usefulness of energy” • High quality - potential energy of sun • Poor quality – thermal energy (heat)

  4. Heat Production from Friction • Heat produced = mechanical energy input x (0.24 cal/J) • Calorie = quantity of thermal energy created by converting 4.184 J of mechanical work • Work = force x distance, work x constant (0.24 cal/J) = heat generated • Energy is conserved – 1st Law of Thermodynamics

  5. Free Energy and the Second Law of Thermodynamics • Thermal energy – portion of total energy attributed to random molecular motion • What part of total energy can be harnessed for useful work? • Randomness or disorder – distinction between high and low quality energy. • F = E – TS (G = H – TS). Free energy = total energy – randomness (entropy) • Temperature affects randomness - TS

  6. Biological Order • If things tend to become more disordered how do living systems develop complex (highly organized) structures?

  7. Units • Length (L) – meters • Mass (M) – kg • Time (T) – seconds • Velocity (LT-1) – ms-1 • Acceleration (LT-2) – ms-2 • Force (MLT-2) – ma, newtons(N) kgms-2 • Energy (ML2 T-2) – Nm or kgm2s-2 • Electric Charge (Q) – coulombs – flow rate of electric current (QT-1) – couls-1 (amperes) • Review prefixes and symbols • Review how to carry through dimensions

  8. Chemistry Review • Avogadro’s number, Nmole, # carbon atoms needed to make up 12 g of carbon. • Volume occupied by a single water molecule? • Molar mass – mass of one mole of atoms (g/mole or Dalton).

  9. Internal energies of molecules • Energy stored in chemical bonds between atoms. • Contributes to value of E, in F = E-TS. • Endothermic/Exothermic reactions • Photons – packets of light energy

  10. Universal Gas Law • Number of gas molecules is proportional to its volume (at atmospheric pressure) • pV = NkBT or from chemisty pV = nRT • kBT = 4.1 x 10-21 J = 4.1 pN nm • kB = gas constant R (8.314 J/molK) / N (6.022 x 1023 molecules per mole)

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